Coevolution of spermatozoa and spermathecae in Lonchopteridae (Diptera).

Across the species of spear-winged flies (Diptera: Lonchopteridae) there is a remarkable variation in size of the female reproductive tract, especially of the spermathecae. In this family there are two tubular spermathecae, which are divided into four morphologically and histologically distinct sections of different lengths and functions. The dimensions of the spermathecae and their individual sections were examined across 11 Lonchoptera species and related to the dimensions of the respective spermatozoa. 3D reconstructions from serial sectioning made it possible to include the volume in these considerations, which is a new approach in this context. Results show that the spermathecae are always longer than the respective spermatozoa. There is a highly significant positive linear correlation between the length of the spermatozoa and the length of the spermathecae in total as well as some of the individual spermathecal sections, suggesting a coevolution of these characters. Moreover, the volume of the spermathecae is much larger in those species with longer and more voluminous spermatozoa, but the volume increase is not sufficient to keep constant the number of spermatozoa that fit within. The observed patterns are discussed with respect to their functional and evolutionary implications, including a new hypothesis on the possible selective advantage of increased spermatozoon length.

Variation of sperm size and evolution of giant spermatozoa in Lonchopteridae (Diptera).

Among species of the spear-winged flies (Lonchopteridae) there is remarkable variation in sperm size, with some species producing giant spermatozoa. With a length of 7500 µm and a width of 1.3 µm the spermatozoon of Lonchoptera fallax ranks among the largest known to date. In the present study body size, testis size, sperm size, and spermatid number per bundle and per testis were examined across 11 Lonchoptera species. Results are discussed in terms of how these characters are related with each other and how their evolution affects the resource allocation amongst spermatozoa. Based on some discrete morphological characters and a molecular tree derived from DNA barcodes a phylogenetic hypothesis of the genus Lonchoptera is proposed. The occurrence of giant spermatozoa in Lonchopteridae is compared to convergent occurrences reported in other taxa.

Morphology and ultrastructure of the spermatozoa of Lonchoptera lutea Panzer, 1809 (Diptera: Lonchopteridae).

Lonchoptera lutea males produce giant spermatozoa that are more than 2000 µm long and 1.4 µm wide. Unlike the typical brachyceran spermatozoon, they have a highly asymmetrical cross-section with only a single, albeit very large, mitochondrial derivative and a pair of massive accessory bodies, one of which extends throughout the entire length of the sperm tail. The accessory bodies consist of an electron-dense matrix in which numerous peculiar electron-lucid substructures are embedded. In the mated female, the giant spermatozoa are found inside two tubular spermathecae which are also extremely long, measuring 4000 µm or more.

A revision of the genus Planinasus Cresson (Diptera, Periscelididae).

The genus Planinasus Cresson is revised and includes 18 extant and one fossil species. We clarify the status of the three previously described species and describe 15 new species as follows (type locality in parenthesis): Planinasus aenigmaticus (Colombia. Bogota: Bogota (04°35.8'N, 74°08.8'W)), Planinasus neotropicus (Panama. Canal Zone: Barro Colorado Island (09°09.1'N, 79°50.8'W)), Planinasus kotrbae (Ecuador. Orellana: Rio Tiputini Biodiversity Station (0°38.2'S, 76°08.9'W)), Planinasus miradorus (Brazil. Maranhão: Parque Estadual Mirador, Base da Geraldina (06°22.2'S, 44°21.8'W)), Planinasus tobagoensis (Trinidad and Tobago. Tobago. St. John: Parlatuvier (11°17.9'N, 60°39'W)), Planinasus xanthops (Ecuador. Orellana: Rio Tiputini Biodiversity Station (0°38.2'S, 76°8.9'W)), Planinasus argentifacies (Peru. Madre de Dios: Río Manu, Pakitza (11°56.6'S, 71°16.9'W; 250 m)), Planinasus insulanus (Dominican Republic. La Vega: near Jarabacoa, Salto Guasara (19°04.4'N, 70°42.1'W, 680 m)), Planinasus nigritarsus (Guyana. Conservation of Ecological Interactions and Biotic Associations (CEIBA; ca. 40 km S Georgetown; 06°29.9'N, 58°13.1'W)), Planinasus atriclypeus (Brazil. Rio de Janeiro: Rio de Janeiro, Floresta da Tijuca (22°57.6'S, 43°16.4'W)), Planinasus atrifrons (Bolivia. Santa Cruz: Ichilo, Buena Vista (4-6 km SSE; Hotel Flora y Fauna; 17°29.95'S, 63°33.15'W; 4-500 m)), P. flavicoxalis (West Indies. Dominica. St. David: 1.6 km N of junction of roads to Rosalie and Castle Bruce (15°23.8'N, 61°18.6'W)), Planinasus mcalpineorum (Mexico. Chiapas: Cacahoatan (7 km N; 15°04.1'N, 92°07.4'W)), Planinasus nigrifacies (Brazil. São Paulo: Mogi das Cruzes, Serra do Itapeti (23°31.5'S, 46°11.2'W)), Planinasus obscuripennis (Peru. Madre de Dios: Río Manu, Erika (near Salvación; 12°50.7'S, 71°23.3'W; 550 m)). In addition to external characters, we also describe and illustrate structures of the male terminalia and for Planinasus kotrbaesp. n., the internal female reproductive organs. Detailed locality data and distribution maps for all species are provided. For perspective and to facilitate genus-group and species-group recognition, the family Periscelididae and subfamily Stenomicrinae are diagnosed and for the latter, a key to included genera is provided.

Unlocking the "Black box": internal female genitalia in Sepsidae (Diptera) evolve fast and are species-specific.

BACKGROUND: The species-specificity of male genitalia has been well documented in many insect groups and sexual selection has been proposed as the evolutionary force driving the often rapid, morphological divergence. The internal female genitalia, in sharp contrast, remain poorly studied. Here, we present the first comparative study of the internal reproductive system of Sepsidae. We test the species-specificity of the female genitalia by comparing recently diverged sister taxa. We also compare the rate of change in female morphological characters with the rate of fast-evolving, molecular and behavioral characters. RESULTS: We describe the ectodermal parts of the female reproductive tract for 41 species representing 21 of the 37 described genera and define 19 morphological characters with discontinuous variation found in eight structures that are part of the reproductive tract. Using a well-resolved molecular phylogeny based on 10 genes, we reconstruct the evolution of these characters across the family [120 steps; Consistency Index (CI): 0.41]. Two structures, in particular, evolve faster than the rest. The first is the ventral receptacle, which is a secondary sperm storage organ. It accounts for more than half of all the evolutionary changes observed (7 characters; 61 steps; CI: 0.46). It is morphologically diverse across genera, can be bi-lobed or multi-chambered (up to 80 chambers), and is strongly sclerotized in one clade. The second structure is the dorsal sclerite, which is present in all sepsids except Orygma luctuosum and Ortalischema albitarse. It is associated with the opening of the spermathecal ducts and is often distinct even among sister species (4 characters; 16 steps; CI: 0.56). CONCLUSIONS: We find the internal female genitalia are diverse in Sepsidae and diagnostic for all species. In particular, fast-evolving structures like the ventral receptacle and dorsal sclerite are likely involved in post-copulatory sexual selection. In comparison to behavioral and molecular data, the female structures are evolving 2/3 as fast as the non-constant third positions of the COI barcoding gene. They display less convergent evolution in characters (CI = 0.54) than the third positions or sepsid mating behavior (CICOI = 0.36; CIBEHAV = 0.45).

A new species of Stigmatomyces from Baltic amber, the first fossil record of Laboulbeniomycetes.

A fossil ascomycete was found attached to the thorax of a stalk eyed fly (Diopsidae: Prosphyracephala succini) in a fragment of Baltic amber. The fungus is assigned to the extant genus Stigmatomyces and described as S. succini sp. nov. This find is the first fossil record of the order Laboulbeniales. At the same time it constitutes the oldest record of a parasitic fungus on an insect. The palaeohabitat is discussed with regard to the find.

A new polymorphic species of Laboulbenia parasitic on a South American fly.

Morphologically different thalli of Laboulbenia richardiana sp. nov. (Laboulbeniales, Ascomycota) were found on various parts of the body of the South American fly Richardia teevani. These thalli lack a separate cell IV and have similar appendages and perithecial apices. They are interpreted here as 'growth forms' of a single biological species. Spore characteristics and insect behavior support this view, rather than the hypothesis of several different species displaying position specificity.